2,3-Butanedione, an Electron-stabilizing Compound, as a Modifier of Sensitivity ofBacillus MegateriumSpores to X-rays

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Abstract
The organic compound 2,3-butanedione (diacetyl) has a high affinity for free electrons, and can stabilize electrons produced by high-energy radiations in aqueous solutions. In the non-metabolizing spore of Bacillus megaterium (buffer suspension at pH 7·0), this compound increases radiation sensitivity in the absence of oxygen as concentration increases up to approximately 4 × 10−3 M. The maximal increase represents 40 per cent of the total observed in the full oxygen effect. Since the compound at maximally effective concentration in the presence of oxygen does not increase radiation sensitivity above that level seen in oxygen alone, it is allowed that the potentiating action of the compound represents one of the actions of oxygen, i.e. oxygen may act in part by stabilizing electrons. Above about 6 × 10−3 M the effectiveness of the compound as a sensitizer decreases, until the anoxic level of sensitivity is reached at 6 × 10−2 M. No suggestions concerning this reversal of effect at high concentrations are offered at this time.